Vulnerability · Published Oct 20, 2026 · Assigned by GitHub_M
CVE-2026-112914filelock: SoftFileLock stale-break restore follows a swapped-in symbolic link and hard-links a file of the user running the lock into the lock directory
Medium 5.3
In plain English
A medium-severity security flaw in filelock from tox-dev. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 5% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
filelock is a platform-independent file lock for Python. From 4.1.0 until 4.2.1, SoftFileLock can restore a stale marker by name after moving it aside, allowing another local user with rename access in a non-sticky lock directory to swap in a symbolic link and, on a runtime that follows the link and a same-filesystem target, make the lock user hard-link one of its files into the lock directory. This issue is fixed in version 4.2.1.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | python-filelock | no fix listed | DEBIAN-CVE-2026-112914 |
| Debian:13 | python-filelock | no fix listed | DEBIAN-CVE-2026-112914 |
| Debian:14 | python-filelock | no fix listed | DEBIAN-CVE-2026-112914 |
| PyPI | filelock | 4.2.1 | GHSA-crv4-6mhj-j5jh |
| Ubuntu:26.04:LTS | python-filelock | no fix listed | UBUNTU-CVE-2026-112914 |
| Ubuntu:26.10 | python-filelock | no fix listed | UBUNTU-CVE-2026-112914 |
Affected products (as reported)
Weakness: CWE-363 · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N
References
- https://github.com/tox-dev/filelock/security/advisories/GHSA-crv4-6mhj-j5jh x_refsource_CONFIRM
- https://github.com/tox-dev/filelock/pull/843 x_refsource_MISC
- https://github.com/tox-dev/filelock/commit/740ff666b62a88496c8d7394e4e6230605e4d62b x_refsource_MISC
- https://github.com/tox-dev/filelock/releases/tag/4.2.1 x_refsource_MISC